Lee Rannals for redOrbit.com — Your Universe Online
Another study is backing up climate change claims, saying Earth is at the warmest it has been in at least 1,400 years. The study shows that the planet has warmed more between 1971 and 2000 than during any other three-decade interval during the model period.
“This paper tells us what we already knew, except in a better, more comprehensive fashion,” study co-author Edward Cook, a tree-ring scientist at Lamont-Doherty Earth Observatory (LDEO) at Columbia University, said in a statement.
The scientists, reporting their findings in the journal Nature Geoscience, also found that Europe’s 2003 heat wave and drought happened during its hottest summer of the last 2,000 years.
“Summer temperatures were intense that year and accompanied by a lack of rain and very dry soil conditions over much of Europe,” said study co-author Jason Smerdon, a climate scientist at LDEO and one of the lead contributors to the Europe reconstruction. Smerdon said that although 2003 sets a record for Europe, global warming was only one of the factors that contributed to the temperature conditions that summer.
The study says that the Medieval Warm Period from about 950 to 1250 AD may have not been a global heat wave. It said that while parts of Europe and North America were warm during this period, South America stayed relatively cool.
Some argue that the natural warming that occurred during the medieval ages is reoccurring today, and that humans are not responsible for the modern day global warming trend.
However, Cook said if we went into another Medieval Warm Period again it would just add to the global warming trend we are already experiencing.
“Distinctive periods, such as the Medieval Warm Period or the Little Ice Age stand out, but do not show a globally uniform pattern,” said co-author Heinz Wanner, a scientist at the University of Bern.
The scientists said the most consistent trend across all regions in the past 2,000 years was a long-term cooling, caused by a rise in volcanic activity, decrease in solar irradiance, changes in land-surface vegetation, and solar variations in Earth’s orbit.
Scientists announced in January that 2012 was the ninth warmest year on record since 1880. However, NASA´s Goddard Institute for Space Studies (GISS) climatologist Gavin Schmidt said that one more year of having high numbers isn’t itself significant.
“What matters is this decade is warmer than the last decade, and that decade was warmer than the decade before,” Schmidt said. “The planet is warming. The reason it´s warming is because we are pumping increasing amounts of carbon dioxide into the atmosphere.”
GISS director James E. Hansen said last year’s temperature is just an example of a new trend of outlying seasonal extremes that are warmer than the hottest seasonal temperature of the mid-20th century.
“The climate dice are now loaded. Some seasons still will be cooler than the long-term average, but the perceptive person should notice that the frequency of unusually warm extremes is increasing. It is the extremes that have the most impact on people and other life on the planet,” Hansen said.